In vitro starch digestion and physicochemical properties of maize starch and maize meal modified by heat-moisture treatment and stearic acid

Abstract

The physicochemical and nutritional properties of heat-moisture treated (HMT) maize starch and maize meal with stearic acid (SA) are studied. The addition of SA followed by HMT produces nongelling starch and maize meal porridge with reduced pasting viscosity. Heat-moisture treatment significantly (P ≤ 0.05) decreases the starch hydrolysis, increases resistant starch, and lowers estimated glycaemic index of both maize meal and maize starch with SA. These changes are due to a more organized crystalline structure between starch polymers and well as the formation of amylose–lipid complexes as shown by differential scanning calorimeter and X-ray diffraction. There seems to be a synergistic effect between HMT and stearic addition as HMT promotes more starch polymer interaction compared to amylose–lipid formation for stearic acid addition. These results suggest that HMT combined with SA can be used to manufacture starch-based functional ingredients and foods with reduced glycaemic index.